The world of DNA origami is no longer flat. The technique, in which hundreds of short oligonucleotides fold and fasten a long single strand of DNA into a predetermined shape, has now been extended into three dimensions. A team led by Jørgen Kjems and Kurt V. Gothelf of Denmark's Aarhus University has created a tiny box to add to the collection of 2-D nanoscale snowflakes, smiley faces, and dolphins that have been constructed through the clever application of DNA origami (Nature 2009, 459, 73). The DNA box measures 42 nm high by 36 nm wide by 36 nm deep—large enough to hold a ribosome or a poliovirus. The researchers equipped the structure with a dual lock-and-key system that pops open the lid of the box in the presence of two short strands of DNA. They also added two fluorescent dyes to the box so they could follow the unlocking process by fluorescence resonance energy transfer. Because the box is able to both sense and react, it could be used as a diagnostic sensor that releases, for example, a medicinal payload under the proper conditions.